[Qemu-devel] [PATCH] qom: Use atomics for object refcounting

[Jan Kiszka <jan.kiszka@siemens.com>]

Objects can soon be referenced/dereference outside the BQL. So we need
to use atomics in object_ref/unref.

Based on patch by Liu Ping Fan.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 qom/object.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/qom/object.c b/qom/object.c
index 803b94b..a76a30b 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -683,16 +683,15 @@ GSList *object_class_get_list(const char *implements_type,
 
 void object_ref(Object *obj)
 {
-    obj->ref++;
+     __sync_fetch_and_add(&obj->ref, 1);
 }
 
 void object_unref(Object *obj)
 {
     g_assert(obj->ref > 0);
-    obj->ref--;
 
     /* parent always holds a reference to its children */
-    if (obj->ref == 0) {
+    if (__sync_sub_and_fetch(&obj->ref, 1) == 0) {
         object_finalize(obj);
     }
 }
-- 
1.7.3.4